U.S. officials have declared a public health emergency for areas along the Gulf of Mexico in the aftermath of Hurricane Katrina.

Health and Human Services Secretary Michael Leavitt made the declaration Wednesday as authorities struggled to rescue survivors and restore order in the region.

In New Orleans, rescue teams continue to pull people from tall buildings and rooftops while engineers try to fix two crucial levees damaged in the storm. Witnesses report dead bodies floating in the water that has submerged about 80 percent of the low-lying city.

In drier areas, police have tried with little success to contain widespread looting. The city's mayor, Ray Nagin says it may be months before evacuated residents can return home.

In the neighboring state of Mississippi, Governor Haley Barbour says Katrina wiped out 90 percent of the buildings near the coast in the cities of Gulfport and Biloxi. Authorities say the unofficial death toll in the area is 110 and they warn it is almost certain to go higher.

U.S. Homeland Security Secretary Michael Chertoff says U.S. officials will work tirelessly to aid the victims of Monday's hurricane. The government says it is sending medical emergency teams and truckloads of basic supplies such as ice and electric generators in an effort to ease the situation.